Studies on Cu(I)-catalyzed synthesis of simple 3-substituted 1,2-allenes and optically active 2-substituted secondary 2,3-allenols
作者:Jing Li、Chao Zhou、Chunling Fu、Shengming Ma
DOI:10.1016/j.tet.2009.02.061
日期:2009.5
methyl ethers, which would react with primary alkyl Grignard reagents under the catalysis of CuBr to afford 3-substituted 1,2-allenes or 2-substituted secondary 2,3-allenols, respectively. The reaction may be applied to the synthesis of optically active 2-substituted secondary 2,3-allenols with up to >99% ee without any protection to the free hydroxyl group in the starting 4-hydroxy-2-alkynyl methyl
Theoretical Support for the Involvement of a Radical Pathway in the Formation of Allenylzincs from Propargyl Iodides and Dialkylzincs: Influence of Zinc Coordination
作者:Suribabu Jammi、Dominique Mouysset、Didier Siri、Michèle P. Bertrand、Laurence Feray
DOI:10.1021/jo302704g
日期:2013.2.15
undergo homolytic substitution at zinc. The stabilization of allenylzinc derivatives by chelation, made possible by the selection of appropriate ortho-substituted 3-phenylalkynyl iodides as precursors, was shown to influence the regioselectivity of their addition to aldehydes and ketones. The more stabilized the chelated allenylzinc intermediate, the higher the ratio of homopropargylic alcohols.
obtained by the reaction of 3-bromo-1-butyne (11) with tributylstibine. The corresponding stiborane (13) reacted with aldehyde to give acetylenic alcohol (14) exclusively in good yield, and the diastereoselectivity was moderately in favour of the threo isomer in the presence of MgBr2. All of the reactions had good chemoselectivity for aldehyde.
Regioselective allylation and propargylation were achieved using acylsilanes as electrophiles and this methodology was applied to the synthesis of PGE3 and F3α methylester.